Add method to get MultiverseWorld from a bukkit world.

src/main/java/org/mvplugins/multiverse/core/world/WorldManager.java

@@ -737,6 +737,17 @@ public class WorldManager {
         return !isLoadedWorld(worldName) && isWorld(worldName);
     }
 
+    /**
+     * Get a world that may or may not be loaded. It will an {@link LoadedMultiverseWorld} if the world is loaded,
+     * otherwise returns an {@link MultiverseWorld} instance.
+     *
+     * @param world The bukkit world to get.
+     * @return The world if it exists.
+     */
+    public Option<MultiverseWorld> getWorld(@Nullable World world) {
+        return Option.of(world).flatMap(this::getWorld);
+    }
+
     /**
      * Get a world that may or may not be loaded. It will an {@link LoadedMultiverseWorld} if the world is loaded,
      * otherwise returns an {@link MultiverseWorld} instance.